MEP and SSEP Signal Loss Caused by Retractor Placement in OLIF Spine Surgery
By Admin | April 01, 2023
At 53, many men’s greatest fear is that their bodies will fail them. No longer able to do the things they did as young men, they can grow resentful and angry. Symptoms such as lower back pain and weakness can be seen as signs that life is on its way downhill. Add in additional discomforts like leg pain, numbness, and tingling, and you hope your dad, uncle, friend, or brother finally has enough motivation to convince them to see a doctor.
After being diagnosed with foraminal stenosis, radiculopathy, and spondylosis, our 53-year-old patient’s surgical team agreed on an L4-L5 Oblique Lateral Interbody Fusion (OLIF) to remove and replace his damaged intervertebral disc.
In order for the surgeon to reach the spine during an OLIF procedure, they have to create a surgical corridor between the psoas muscle and the peritoneum. This corridor is then held open using retractors so that the surgeon can access the affected parts of the patient’s spine and alleviate their symptoms. However, if incorrectly placed, the retractors used to hold the corridor open can create a risk of nerve compression or damage during the procedure.
To prevent this from happening, monitoring sensory and motor functions during the procedure can help ensure that the retractors are placed in an ideal position (one that doesn’t compress or damage the patient’s nerves). During this surgery, the neuromonitoring equipment used to monitor the patient’s sensory and motor functions included somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), triggered (tEMG) and spontaneous (sEMG) electromyography.
As the surgeon created the surgical corridor to access the spine, the tEMG was used to ensure no nerves were cut or damaged in the process. However, during the spinal fusion, the left saphenous SSEP response’s amplitude decreased and the left quadricep’s MEP response disappeared. These changes signaled to the team that there was a problem with the placement of the surgical retractors.
Once the team removed the surgical retractors, the patient’s somatosensory evoked potentials and motor evoked potential responses returned to baseline.
Without neuromonitoring, the possible consequences of conducting this procedure could have included cut or damaged nerves (during the creation of the surgical corridor) or damage to the femoral nerve (as a result of retractors that weren’t ideally placed). These consequences could have resulted in postoperative sensory or motor deficits such as femoral nerve palsy, making the patient incapable of feeling or moving his leg.
Axis Neuromonitoring provides high-quality intraoperative neurophysiological monitoring (IONM). For more information about neuromonitoring and how our practices create the best patient outcomes, call 888-344-2947 or visit https://www.axisneuromonitoring.com.
